Premature ovarian insufficiency (POI), also referred to as premature ovarian failure (POF) or premature menopause, is a prevalent reproductive disease in women characterized by oligomenorrhea and elevated serum FSH level, leading to diminished ovarian function [1]. The prevalence of POI among women under 40 years old is approximately 1 %, while it is around 0.5 % for those under 35 years old, and the incidence exhibits an annual trend on an annual basis [2]. At present, about 25 % of all forms of POF can be classified as iatrogenic and related to cancer treatment such as chemotherapy or radiotherapy [3]. The progress achieved in cancer diagnosis and treatment technology over the last decade has led to a notable improvement in the 5-year survival rate for female cancer patients. This underscores the significance of enhancing the post-treatment quality of life for this patient population. Among these, adolescents and women of childbearing age face an elevated risk of ovarian dysfunction and reproductive damage due to heightened follicle development and increased chemotherapy drug sensitivity, leading to phenomena like follicle atresia [4]. Therefore, it is imperative to devise strategies for preventing and managing chemotherapy-induced ovarian damage in women, with a specific focus on preserving female fertility.

It is well-established GCs being the primary site of estrogen synthesis, also play a crucial role in ensuring the development of an optimal oocyte microenvironment [5]. The reduction in viability and secretion function of GCs induced by chemotherapy can directly dysregulate follicular development, leading to female reproductive disorders [6]. Emerging evidence also suggests that chemotherapy-induced ferroptosis in GCs can result in ovarian dysfunction [7].

Ferroptosis is a novel form of cellular demise that depends on the accumulation of lipid peroxides caused by iron ions [8]. Following binding to transferrin (TF), Fe3+ is internalized into cells through the transferrin receptor (TFR) located on the cell membrane, where it undergoes reduction to Fe2+ mediated by six-transmembrane epithelial antigen of prostate 3 (STEAP3), and the divalent metal transporter 1 (DMT1) facilitates the release of Fe2+ into the cytoplasm, leading to the formation of a labile iron pool (LIP), representing a free and unstable intracellular Fe2+ reservoir [9]. When cells are stimulated by external stimuli, the expression of proteins involved in iron homeostasis is dysregulated, leading to an excessive accumulation of free Fe2+, which triggers the Fenton reaction and results in the generation of reactive oxygen species (ROS) and subsequent lipid peroxidation and induces ferroptosis [9,10]. Additionally, glutathione peroxidase 4 (GPX4) protects against lipid peroxidation by facilitating the synthesis of reduced glutathione (GSH), and the depletion of GSH and inactivation of GPX4 disrupts the cellular antioxidant defense system, thereby promoting lipid peroxidation and triggering ferroptosis [11]. Ferritin serves as the principal intracellular protein complex for iron storage, comprising ferritin light chain (FTL) and ferritin heavy chain 1 (FTH1). On the one hand, the process of ferritin-mediated iron storage primarily involves Fe2+ oxidation and subsequent Fe3+ transfer to maintain iron storage in ferritin. On the other hand, ferritin possesses the ability to sequester free Fe2+ and effectively suppress the Fenton reaction [12]. The induction of autophagy triggers the translocation of ferritin to lysosomes for degradation, thereby facilitating the release of Fe2+ and subsequent initiation of the Fenton reaction and lipid peroxidation. During this process, nuclear receptor coactivator 4 (NCOA4) plays a key role in ferritin autophagy as a selective cargo receptor for transporting FTH1 to lysosomes [13,14]. Therefore, ferritinophagy is considered a pivotal mechanism that triggers ferroptosis. In a previous investigation, we demonstrated that cyclophosphamide (CTX), a commonly used chemotherapeutic agent, induces excessive autophagy in ovarian GCs [15]. Accordingly, we hypothesized that CTX may contribute to or exacerbate ferroptosis by inducing ferritinophagy in GCs.

Human umbilical cord mesenchymal stem cells (hUC-MSCs) have been extensively utilized in the field of POI/POF treatment in recent years owing to their exceptional properties, and several clinical trials have demonstrated the capacity of hUC-MSCs to enhance therapeutic effectiveness for patients with POI/POF [16,17]. However, the precise mechanism underlying the regulatory effects of hUC-MSCs on ovarian function improvement remains to be elucidated. Our previous studies have demonstrated that hUC-MSCs can improve ovarian function by alleviating excessive autophagy of GCs caused by CTX [15]. Therefore, we propose the following hypothesis: hUC-MSCs exert a resistant effect against ferroptosis in GCs and consequently improve ovarian function in POI mice model, mediated by the suppression of ferritinophagy and attenuation of reactive oxygen species (ROS) accumulate.

In this study, we assessed the impact of hUC-MSCs on CTX-induced POI mice model, revealing their effectiveness in reversing CTX-induced ovarian dysfunction through the attenuation of ferritinophagy-mediated ferroptosis in GCs. This study not only elucidated the fundamental mechanism by which hUC-MSCs ameliorate POI but also laid the groundwork for targeted clinical augmentation of GCs in the management of POI/POF disorders.